Development and processing of flame retardant cellulose acetate compounds for foaming applications

Cellulose acetate (CA) is a bio‐based polymeric material suitable to replace foamed polystyrene (PS) boards in applications for building insulation. Foam boards can be produced by extrusion foaming with physical blowing agents. In addition, the high heat deflection temperature and good mechanical properties (e.g., tensile and compression strength) of CA make it suitable for the injection molding of technical parts. In general, flame retardancy of foamed products is often required in building or electronic applications. This article presents the effects of various flame retardant (FR) additives, process settings, and the calibration of the foam board on flammability, foam morphology, and mechanical properties of extruded CA boards. Different formulations of FR additives and foaming agents were investigated regarding density and morphology of the foamed boards. Furthermore, investigations on foam behavior for foam injection molding with physical blowing agents were conducted. The foamed parts were characterized with regard to their flammability.